I would be - HRH The Princess Daenerys Targaryen, Khaleesi of the Dothraki..
and later..
HM Queen Daenerys I of the Seven Kingdoms of Westeros, First of Her Name, Queen of Meereen, Queen of the Andals and the Rhoynar and the First Men, Protector of the Realm, Khaleesi of the Great Grass Sea

__________________Ś i vethed...nā i onnad. Minlū pedich nin i aur hen telitha. - Arwen & Aragorn, The Lord of the Rings(English translation: "This is not the end... it is the beginning. You told me once, this day would come.")

Well, I dressed up as Little Red Riding Hood for Halloween when I was 5 years old, and I liked that in the movie The 10th Kingdom there was a character named 'Queen Riding Hood III of the 2nd Kingdom' (and the House of Red). Highly fictious of course! If I'm going for real-life, I'd probably choose something Prussian or German from the area of my ancestors. I'd have the title, some jewels and a schloss, but none of the hinderances that come from being a member of a ruling family.